Non-Language Environment conforming assembler routines

When you run a non-Language Environment-conforming routine in Language Environment, you must observe the following conventions:

• R13 must contain the address of the executing routine's own register save area
• The register save area back chain must be set to a valid 31-bit address (if the address is a 24 bit address, the first byte of the address must be hex zeros)
• The first two bytes of the register save area must be hex zeros